1. Field of the Invention
The present invention relates to a power transmission control device for vehicle capable of controlling a change gear ratio when an internal combustion engine is started with an electric rotating machine acting as a start-up motor and when the electric rotating machine acting as an alternator or auxiliary machines are driven from the internal combustion engine.
2. Description of the Related Art
Auxiliary machines such as compressor or oil pump, charging generator (alternator) and the like are mounted on a vehicle driven by an internal combustion engine and the internal combustion engine drives these auxiliary machines. FIG. 6 shows a prior art of a drive of these auxiliary machines, and is a cross sectional view showing a technique disclosed in the Japanese Patent Publication (examined) No. 58069/1994.
This auxiliary machine drive includes a disk-shaped carrier 102 accommodated in an internal part of a housing 101, and an input shaft 103 rotatably supported on the housing 101 is formed integrally with this carrier 102. Furthermore, a plurality of arms 102a are protruded on a surface opposite to the input shaft 103 of the carrier 102, and a planetary gear 104 is mounted rotatably on each arm 102a. The planetary gear 104 is engaged with an internal gear 105 on the outer circumferential side, and with a sun gear 106 on the inside perimeter side with respect to the input shaft 103. The planetary gear 104, the internal gear 105 and the sun gear 106 form a planetary gear mechanism, and the internal gear 105 is rotatably supported on the housing 101 on the circumferential side through bearings 107a and 107b. 
The sun gear 106 is formed on an output shaft 110 in such a manner that one end is rotatably journaled on the carrier 102 integrated with the input shaft 103 via a bearing 108, and the other end is rotatably journaled on the housing 101 via a bearing 109. A pulley 111 for driving the auxiliary machine is put over the output shaft 110. Further, a semple plunger 112 is provided on a circumference of the carrier 102 in such a manner as to be protruding in radial direction. The semple plunger 112 is constructed so as to protrude from the carrier 102 due to a centrifugal force thereby fixing the carrier 102 and the internal gear 105 when a rotational speed of the carrier 102 exceeds a predetermined level. An electromagnetic clutch 113 is provided at one end face of the internal gear 105. This electromagnetic clutch 113 consists of an umbrella-shaped spring 113a provided on a side surface of the internal gear 105, a ring-shaped armature 113b fixed to a larger diameter portion of the spring 113a, and a core 113d that is disposed opposite to the armature 113b and provided with an exciting coil 113c. 
In the conventional auxiliary machine drive of above construction, when the input shaft 103 is driven from an internal combustion engine to rotate, the planetary gear 106 revolves round the sun gear 106 that is supported on the arm 102b provided at the carrier 102 formed integrally with the input shaft 103. At this time, an ON state of the electromagnetic clutch 113 causes the armature 113b of the electromagnetic clutch 113 to be attracted to and constrained by the core 113d against the spring 113a. Accordingly, the internal gear 105, which is connected to the armature 113b via the spring 113a, is also in a stationary state. Therefore, the sun gear 106 rotates at an increasing speed compared with a rotational speed of the input shaft 103, and the output shaft 110 on which the sun gear 106 is formed, comes to rotate at a high speed compared with the input shaft 103.
When increasing an engine speed of the internal combustion engine, and a rotational speed of the carrier 102 comes to be not less than a predetermined value, the semple plunger 112, which is provided on the circumferential portion of the carrier 102, protrudes in radial direction due to a centrifugal force, and is engaged with the internal gear 105 resulting in connection between the carrier 102 and the internal gear 105. Furthermore, when a rotational speed of the carrier comes to be not less than a predetermined value, control means, not shown, causes the electromagnetic clutch 113 to be in an OFF state, and releases constraint of the internal gear 105. Therefore, the internal gear 105 comes to rotate integrally with the carrier 102, that is, the input shaft 103, and the sun gear 106 also operates at the same rotational speed as that of the carrier 102 to prevent the output shaft 104 and the auxiliary machine from over-rotation. In this manner, this mechanism prevents the output shaft 104 and auxiliary machine from being damaged due to any excessive centrifugal force, and prevents bearings and the like from being damaged due to over-rotation.
Since the conventional auxiliary machine drive is constituted as described above, a problem exits in that switching between a speed increasing mode and a constant speed mode is not smooth. Specifically, the auxiliary machine is arranged such that the semple plunger 112 protrudes owing to a centrifugal force to be engaged with the internal gear 105 thereby providing connection between the carrier 102 and the internal gear 105. Accordingly, shock at the time of switching is large, this shock is transmitted to the internal combustion engine via the input shaft 103, and any rotational fluctuation is brought about to the internal combustion engine. As a result, a problem in vehicle drivability comes out.
Moreover, switching between a speed increasing mode and a constant speed mode is determined primarily depending on a centrifugal force exerting on the semple plunger 112, i.e., an engine speed of the internal combustion engine. Therefore, in the case of controlling the charging generator for increasing speed, another problem exists in that conditions of electrical loads or a remaining capacity of a battery is not involved. A further problem exists in that switching cannot be carried out under optimum conditions utilizing various signal data such as cooling water temperature of the internal combustion engine, vehicle velocity, and shift position location.